This invention relates to supports for signal carriers, and particularly to supports for triplate centre conductors.
A typical known triplate is shown in FIG. 1. It comprises a pair of parallel conductive ground planes 1 and 2 and a central conductor 3 between and parallel to them.
The central conductor 3 is held in position by being sandwiched between two dielectric sheets 4 and 5. The sheets 4 and 5 are secured to the ground planes 1 and 2 and are equal in thickness to ensure that the central conductor 3 is held equidistant from the two ground planes 1 and 2.
Another way of supporting the centre conductor is shown in FIG. 2. A triplate conductive ground plane 6 supports a plurality of dielectric strips 7 all of equal thickness. The strips 7 in turn support a centre conductor 8, because the dielectric strips 7 are all of equal thickness the centre conductor 8 is held parallel to the ground plane 6. A second plurality of dielectric strips secured to a second ground plane would be placed on top of the centre conductor 8 to hold the centre conductor 8 equidistant between the two ground planes. This is not shown, for clarity.
There are disadvantages to both of these constructions. The use of continuous sheets of dielectric material results in the triplate structure being a lossy transmission line, while the use of separate dielectric strips is expensive because placing and securing the large numbers of individual dielectric strips required is very time consuming.
This invention was intended to at least partially overcome these problems.